I deleted the node folders from mine and copied from another system
There index created with Custom_Casing_Analyzer settings.

In Kibana when i execute GET /Student/_settings

    {
      "Student": {
        "settings": {
          "index": {
            "number_of_shards": "5",
            "provided_name": "Student",
            "creation_date": "1518524267463",
            "analysis": {
              "analyzer": {
                "Custom_Casing_Analyzer": {
                  "filter": [
                    "lowercase"
                  ],
                  "type": "custom",
                  "tokenizer": "keyword"
                }
              }
            },
            "number_of_replicas": "1",
            "uuid": "SPo0vE6OTc-K6BcYQo04rw",
            "version": {
              "created": "6010199"
            }
          }
        }
      }
}

But while getting data, trying to PutMapping for the column, need to avoid case check, there getting conflict issue

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